A ceramic composition mainly composed of alumina (Al2O3) has relatively excellent mechanical properties, reaction resistance and heat resistance and is accordingly used for tools, structural members and structural components. An alumina/tungsten carbide-based ceramic composition is a ceramic composition produced by adding tungsten carbide (WC) to alumina and has more excellent mechanical properties and heat resistance. Accordingly, the alumina/tungsten carbide-based ceramic composition is used for, for example, cutting tools and molds (see, for example, Patent Literatures 1 and 2).
An alumina/tungsten carbide/zirconia-based ceramic composition is a ceramic composition produced by further adding zirconia (ZrO2) to alumina and tungsten carbide and has furthermore excellent mechanical properties. Accordingly, the alumina/tungsten carbide/zirconia-based ceramic composition is usable for, for example, a cutting tool for a heat-resistant alloy that needs further higher impact resistance and heat resistance (see, for example, Patent Literature 3).
A whisker-type ceramic composition is often used for the cutting tool for the heat-resistant alloy. The whisker-type ceramic composition is a ceramic composition produced by adding silicon carbide whisker to alumina. The whisker-type ceramic composition, however, has problems that the silicon carbide whisker used as the raw material is relatively expensive and that careful handling is required to avoid a potential health hazard caused by the silicon carbide whisker of needle crystals. The alumina/tungsten carbide/zirconia-based ceramic composition provides the mechanical properties and the durability substantially equivalent to those of the whisker-type ceramic composition and is additionally superior to the whisker-type ceramic composition in the cost and the low risk of health hazard.